A chop saw (also a miter saw, a compound miter saw, a sliding compound miter saw, etc.) is a power tool, which may be used to make a quick crosscut in a workpiece, such as a piece of lumber, trim, etc. It may be used to cut wood, although some plastics and light metals may also be cut with the tool. Common uses include framing operations and the preparation of crown molding or other types of trim. A chop saw may be considered a lightweight circular saw mounted on a spring-loaded pivoting arm supported by a metal base. Chop saws may be relatively small and portable, with common blade sizes ranging from eight to twelve inches. While these relatively small saws may not have the cutting capacity of a radial arm saw, they may be very portable and rugged enough to stand up to daily use (and abuse) on the job.
Depending on the chop saw, a number of cuts may be made. For example, a basic chop saw may cut a workpiece at a 90° angle or perpendicular to the table supporting the work piece. A miter saw may allow for rotation of the saw head relative to the workpiece, thus, providing angular cuts within a given range, common angles may include 15°, 30°, or 45°. In addition, some chop saws, referred to as compound miter saws, may make bevel cuts, which may include cuts angled relative to the horizontal plane of the support table.
If you tilt the blade while cutting at an angle, these saws may be able to cut trim or molding while the stock lies flat on the table. But tilting the blade means that there must be clearance at the fence when the saw head heels over. To achieve this, the height of the fence near the blade may be reduced, and users may be advised to add a supplemental wood fence when making regular cuts that may need extra-height support. In addition, sliding fence may be used, which provides full-height support and moves out of the way for bevel cuts.
Preset detent positions on the saw's turntable (typically set at 0, 15, 22.5, 30, and 45 degrees) may help to position the blade for common miter cuts. Some manufacturers also offer detents for the common crown molding angles on the miter and bevel scales. But the detents on some saws may be tricky to override if you want to make minute adjustments to the fit of a cut—say, a 32.25-degree miter instead of the 31.62 degrees that crown molding typically requires. The miter and bevel scales offered by different manufacturers may not be equally easy to read, either. For example, bevel scales may be partially hidden behind the body of the saw.
A number of steps may be taken to use a chop saw to create a cut on a workpiece. A workpiece may be marked for cutting with either a line or a mark. The workpiece may then be placed on the chop saw table with two hands and positioned with two hands such that the line or mark is approximately in line with the blade. One hand may be released from the workpiece to grip the handle of the saw while the second hand continues to hold the workpiece down and against the fence of the chop saw. The saw head may be lowered with the blade either stationary or running to touch down on the workpiece to see how much adjustment of the workpiece is necessary to line the blade with the mark. The saw head may then be released back to the “up” position and both hands may be placed back on the workpiece to adjust it relative to the blade. (It is usually very difficult to accurately adjust a workpiece of any size with one hand.)
The steps of releasing one hand from the workpiece, lowing the saw head with that hand to determine the degree of adjustment necessary to make a proper cut, and then readjusting the workpiece may be repeated until the workpiece is properly positioned (this frequently takes 3-4 iterations). A cut may then be made by turning on the saw and pulling the chop saw through the workpiece.
To help with gross positioning, some saws may be equipped with a laser. With a laser, the saw blade may not need to be brought down to the work piece during adjustment. However, the laser may have a finite width and determining very accurate cuts through the laser alone may be difficult. Also, an iterative process is still required to finely adjust what could be a large, heavy workpiece to a laser line.
In addition, cutting a workpiece to less than 1/32″ (0.032″) of its ideal length may require an extensive amount of time positioning the work piece to get an accurate cut. The number of iterations to get an accurate cut may be increased by the fact that a user needs to be conservative in determining where he/she makes a cut; you can always cut more off, but you can't add it on.